Rail flaw detector mechanism



Aug. 12, 1941.

J. H. BIGELOW RAIL. FLAW DETECTOR MECHANISM Filed July 30. 1937 GiGG v IN VEN TOK 3 (.Jllifl If Bye/0n I TORNE Yj Patented Aug. 12, 1941 RAIL FLAW DETECTOR. MECHANISM Julian H. Bigelow, Brooklyn, N. Y., assignor to Sperry Products, Inc., Brooklyn, N. Y., a corporation of New York Application July so, 1931, Serial No. 156,465

Claims.

This invention relates to rail flow detector mechanism of the type disclosed in the Sperry rail flow detector car. The principle of operation of said car is now well known and is disclosed, for example, in the U. S. Patent to Harcourt 0. Drake, No; 2,074,742 granted March 23, 1937. Essentially, such car consists inagenerator within the car body for supplying current to spaced points on the rail through sets of current brushes carried by a current brush carriage which is held in engagement with the rail by means, such as fluid pressure, operating to depress pis tons within cylinders. The current thus sent through the rail establishes an electromagnetic field surrounding the raiL'which field is uniform except in the region of flaw, where it is distorted. For detecting the presence of flaws, such distortions are caused to generate an'EMF in a pair of flux responsive devices which are moved through said field in constant relation to the rail head. Normally, the devices, which are arranged in tandem, will cut the same number of lines of force, but on entering a region of flaw, first one and then the other of said devices will cut a different number of lines of force to generate a differential EMF which after being suit-v ably amplified may be caused tooperate indicators, such as a recorder in the car and a paint gun carried by the current brush carriage and adapted. to squirt paint upon the rail. in the region of flaw'.

The said flux responsive devices, which in the Sperry car and in the said Drake patent take the .iorm of induction coils, are supported in a housing which is mounted upon a detector carriage adapted to rideupon the rail, the said detector carriage being mounted on the current brush carriage in such manner as to permit movement of the detector carriage independent of the current brush carriage within certain limits so that the detector carriage may align itself with the irregularities of the rail surface so that the coils are at all times parallel to the rail surface.

It will be understood that in the mechanism described above it is essential that the coilsbe maintained in substantially constant relationship with respect to the railhead. As described in the said Drake patent, theconstruction is such that the coilsare maintained always at a constant distance above the rail surface. However, it is possible, because of the independent movement of the detector carriage relative to the current 'brush carriage, that the coils may move laterally of the rail and in so doing cut a variable number of lines of force to generate a diiferential EMF as in the case of a flaw. Thus an indication would be obtained of an internal defect where in fact none existed. Inorder to maintain the detector mechanism in constant relation transversely with. respect to the rail head as well as vertically, it has been proposed, as in the U. S. patent to George L. Jones No. 1,870,811, granted August 9, 1932, to have the wheels upon which the current brush carriage rides on the rail mounted askew or toed in, that relative to the current brush carriage.

It is) the principal object of my invention, therefore, to provide mechanism which will ensure constancy of relationship between the detector carriage and the rail surface, not only vertically as in the said Drake patent, but also transversely with respect to the longitudinal axis of the rail. For this purpose, I provide a different mounting of the detector carriage on the current brush carriage from that shown in the said Drake patent. Said mounting will be described more in detail in the following description.

In the accompanying drawing,

Fig. 1 is aside elevation ofa portion of a Sperry rail flaw detector car showing the current brush carriage and the detector carriage mounted thereon by the mounting. which constitutes myinvention.

Fig. 2 is an enlarged view of the detector carriage and its mounting. Fig. 3 is a scction taken substantially on the line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 3, but showing a the carriage shown in ported on the rail by means such as flanged 32 carried by the frame 26.

wheels l3, H. The frame is suspended from a car body l6 by means such as piston rods is pivotally connected at their lower ends to the frame In and connected at their upper ends to pistons operating within cylinders ll supported on the car body. Fluid under pressure may be supplied to said cylinders when it is desired to lower the carriage into engagement with the rail; but when said fluid under pressure is cut oil, the carriage is automatically raised by means such as springs (not shown) and cables l9. With the carriage in lowered position, current from a generator G within the car body is supplied to the sets of brushes to send current through the rail between said spaced sets of brushes to establish an electromagnetic field surrounding the rail, which field will be uniform as hereinbefore described, except in the region of flaw where the field will be distorted. Such distortions may be detected by one or more sets of detector coils 20 arranged in tandem within a housing 2! and oppositelyconnectedso that variations in the current supply through the rail will afiect said coils equally and oppositely to nullify the effect of' such variations. The said housing 2| may be supported on a detector carriage 22 adapted to ride upon the rails as by means of sets of wheels 23 which maintain the detector coils and the housing in fixed relationship with respect to the top of the rail, that is, at a constant distance vertically above the rail. The said detector carriage 22 may be mounted upon the current brush carriage by means of bolts 24 connected at their lower ends to the detector carriage and extending loosely through bushings 25 in a bracket 26 attached to the under side of the current brush carriage, Springs 21 interposed between the detector carriage 23 and the under-side of bracket 26 tend to maintain the detector carriage firmly in engagement with the rail surface.

Heretofore, the said springs exerted their force axially through the bolts 24 so that the compressive force of the springs was exerted normal to the carriage 23., In the present invention, however, I modify the said mounting and also certain of the wheels of the carriage. so that I may obtain a directive force which will tend to maintain the detector carriage in fixed relationship transversely with respect to the longitudinal axis of the rail and the direction of travel of the detector car. For this purpose, instead of passing bolts 24 through fixed bushings in the bracket 26, I cause said bolts to pass through blocks 30.

Said blocks are pivotally mounted in the bracket 26 for movement about an axis 28 which is displaced from the axis of bolts 24 a distance L in a direction transverse to the longitudinal axis of the rail. Stops 32 carried by bracket 26 and overhanging each block 30 limits the upward movement thereof. The effect of such mounting may be seen in Fig. 5. The spring 21 pressing upwardly against blocks B causes movement of each block with its bolt 24 and spring 2'l around pivot 28 through torque arm L to cause carriage 22 to swing in a rotary direction around the pivot 28 of said blocks. The rotary movement of the blocks in said direction is limited by the stops The shaft 39 of pairs of wheels 23 may be provided with a flange 45 adapted to bear against the gage side of the railhead so that the rotary movement of the blocks 30 around the pivot 28 induced by the springs will cause said flange to engage firmly with the gage side of the railhead. Obviously this will maintain the detector carriage in constant relationship laterally with respect to the longitudinal axis of the rail. One such flange 45 may be provided on a wheel at each end of the detector carriage.

One of the principal advantages of the above described construction lies in the fact that the means for biasing the wheel flanges 45 toward the gage side of the rail is not rendered eifective until the detector carriage engages the railhead and compresses springs 21. Therefore upon raising the detector carriage out of engagement with the rail there is no tendency for the carriage to be swung laterally a substantial distance, and therefore no means is required to pull the carriage back so that flanges 45 may clear the rail and permit the detector carriage to be lowered into engagement with the rail.

In Fig. 3, the blocks are shown mountd on the single pivotal shaft 28 which extends completely across the carriage 26. This is in many ways a preferable form because twisting of the carriage, due to one of the blocks rotating around its axis while the other does not, is avoided, but, if desired, each block may be separately mounted on an individual pivotal shaft 28' as disclosed in Fi 4.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent .the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a flawdetector for rails, a support adapted to travel along the rail, a carriage adapted to travel along the rail and having means for contacting the gage side of the rail, a detector mechanism mounted on said carriage, means for mounting said carriage on said support, said last-named means including a bolt connected at its lower end to said carriage and extending upwardly a, block engaging the upper end of said bolt, said block being pivotally mounted on said support for movement about an axis offset from the vertical axis of said bolt in a direction transverse of the rail, and means for moving said block around said pivotal axis in a direction to cause said contacting means to engage the gage side of the railhead.

2. In a flaw detector for rails, a support adapted to travel along the rail, a carriage adapted to travel along the rail and having means for contacting the gage side of the rail, a detector mechanism mounted on said carriage, means for mounting said carriage on said support, said last-- named means including a plurality of bolts each connected at its lower end to said carriage and extending upwardly, a plurality of blocks each engaging the upper end of a respective bolt, said blocks being pivotally mounted on said-support for movement about an axis offset from the vertical axes of said bolts in a direction transverse of the rail, and means for moving said blocks around said pivotal axis in a direction to cause said contacting means to engage the gage side of the railhead.

3. In a flaw detector for rails, a support adapted to travel along the rail. a carriage adapted to travel long the rail and having means for contacting the gaze side 01 the rail. a detector mechanism mounted on said carriage, means for mounting said carriage on said support, said lastnamed means including a plurality of bolts each connected at its lower end to said carriage and extending upwardly. a plurality of blocks each engaging the upper end of a respective bolt, said blocks being pivotally mounted on said support on a single pivot for movement about an axis oilset from the-vertical axes of said bolts in a direction transverse of the rail, and means for moving said blocks around said pivotol axis in a direction to cause said contacting means to engage the gage side oi the railhead.

4. In a flaw detector for rails, a support adapted to travel along the rail, a detector mechanism mounted on said support and having means for contacting the gage side of the raiihead, means for raising said mechanism to ineflective position out of engagement with the rail and for lowering 3 said mechanism into engagement with the rail,

-.and means rendered eii'ective by the engagement of said detector mechanism with the rail tor moving said mechanism relative to said support in a direction for causing said contacting means to engage the gage side oi. the railhead.

5. In a flaw detector for rails, a support adapted to travel along the rail, means for raising and lowering'said support. a detector mechanism roman n. nreanow. 

